Inexpensive circular LED mill/drill light

Anyone who uses a drill or mill knows how difficult it can be to get the right light on the part you are machining. If the light is near you, you cast shadows as you move your hands in to manipulate the piece, and the light fixture can get between you and the piece. If the light is behind the piece, then you can get glare in your eyes. The best approach is a circular light, mounted around the mill itself.

After seeing the amazing circular LED lights that my friend, Ralph Lemnah, made, I wanted one. I was not, however, willing to put as much work into my light as he did (he designed the circuits, designed the PC board, fabricated the PC boards, fabricated the enclosures, and then fabricated the mounting brackets!)

It costs $18 with free shipping. While it claims to require 220 V AC to run, it actually runs just fine on 110 V AC. It is manufactured with four quadrants, each of which contains 22 LEDs and its own little power supply board; each power supply produces 62 volts. This voltage is too high to repurpose these devices for use with a regular wall wart.

Note that the insulation on these wires is the softest I have ever seen: you can strip the wires easily with your finger nails. You should not allow these wires to be exposed to rough use.

Here are some shots of the device after I disassembled it. Note the metal backed PC board used for the quadrants.

I made a wooden adapter plate so that I could mount it to my mill. I considered doing it “right”, with aluminum, but it seemed a shame to throw away so much aluminum to make the ring. The inner diameter of the plate just fits around the mill; I used a notched threaded rod as a set screw to keep the plate from dropping off of the mil (see red circle in the first picture)l. And, yes, the cable ties are ugly. Still, the whole process only took an hour or so. I was careful to use a cable tie to ensure that an accidental pull on the power wire would not affect the soft insulation on the original wires.